1. Field of the Invention
The present invention relates to a vehicle-use air bag module, and more particularly to a vehicle-use air bag module which hardly exerts influence on a side end portion of a module cover even when an external force or heat is applied to the module cover.
2. Description of Background Art
Conventionally, the optimum structure of an air bag module for integrally housing a folded air bag and an inflator for inflating and deploying the air bag has been studied. As an example, a structure is known for housing the air bag and the inflator in a casing made of metal or the like. An opening portion of the casing is covered with a module cover made of a resin or the like. Usually, such a module cover is configured such that a tear line which constitutes a fragile portion is formed in a top plate member thereof. When the inflator is operated, the tear line is broken thus inflating and developing the air bag.
JP-A-2001-63504 discloses an air bag module formed by overlapping a side wall of the casing and a plate-like portion extending downwardly from a side end portion of the module cover. Both members are joined using rivets.
In mounting the air bag module on a motorcycle, to protect the tear line from moisture, dust or an unpredicted external force or the like, the tear line may be formed in the above-mentioned plate-like portion in place of the top plate member. Further, by constituting the air bag module such that the side end portion of the module cover extends outwardly and the side end portion is engaged with a neighboring exterior part, the tear line is concealed from the outside. Thus, the tear line protective effect can be further enhanced. However, the simple outward extension of the side end portion is liable to easily lower the rigidity of the extended portion. Thus, it is desirable to take the influence such as an external force or heat on the side end portion into consideration. However, JP-A-2001-63504 fails to suggest the above-mentioned task.